Siemens SIMATIC S7-1500 System Manual page 414

(1) Primary CPU switches to the RUN operating state
Figure 12-11 Primary CPU switches to the RUN operating state
Table 12- 14 Response to loss of redundancy of CPU: Primary CPU switches to RUN
No. in Primary CPU
diagram
Initial situation: The S7-1500R/H redundant system is in the RUN-Redundant system state.
The backup CPU fails because of a hardware defect.
① The CPU switches from RUN-
Redundant to RUN. The CPU be-
haves like a standard CPU and con-
tinues to process the user program.
Error elimination procedure for redundant operation
1. Eliminate the error.
2. Start the backup CPU.
The backup CPU switches from the STOP operating state to the SYNCUP operating state.
Synchronization starts as detailed in the section SYNCUP system state (Page 388).
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
System state
RUN-Redundant → RUN-Solo
12.4 Operating and system states
Backup CPU
Following the error, the CPU switches
from the RUN-Redundant operating state
to STOP or POWER OFF.
Commissioning
413